MP3Surround

MP3 Surround

Introduction

MP3 Surround is a new type of MP3 that supports 5.1 channels of audio. MP3 Surround files have the extension *.mp3 like normal stereo MP3 files. That is possible as MP3 Surround encoded MP3-files are completely backwards compatible with standard MP3. Normal Hardware and Software MP3-players treat and report MP3 Surround encoded MP3 files as standard stereo MP3 as they do not recognize the surround extension.

So everyone might already own some MP3 Surround encoded MP3 files but does not know about it ...

Players for MP3 Surround

Due to the backwards compatibility to MP3, any hardware and software MP3 player should be able to play MP3 Surround encoded files without any problem - although in stereo only. For the playback of the 5.1 content of MP3 Surround files, only three software-based possibilities exist at the moment: there is a Winamp plugin and a standalone player, both provided by all4mp3.com. The newest DivX player in the version 6.3.x and above can decode DivX-encoded movies with an MP3 Surround encoded audio layer.

Internet Streaming

Official streaming solutions for broadcasting MP3 Surround across the internet do not exist at the moment - but that might change sooner or later. Inofficial streaming solutions might be possible after tweaking the Icecast streaming server or by using the built in streaming capabilities of the VLC media player.

MP3 Surround Technology

The MP3 backwards compatibility of MP3 Surround has been achieved by downmixing six discrete audio channels to two stereo channels (!) while a third channel (the "surround" channel) outside the stereo MP3 frames contains the dispatching information (the surround info) necessary to get back the full 5.1 content. This third channel is invisible for normal MP3 players (as it is outside the defined MP3 frame structures), they treat the surround channel as they would treat id3 tags: they don't recognize them for playback. The data overhead needed for the third surround channel is 16 kbit/s, which allows for file sizes similar to standard stereo MP3 files.

MP3 Surround has been developed by the fathers of MP3, the Fraunhofer IIS and Thomson in 2004. MP3 Surround is the high-bitrate (128-320kbps) cousin to the currently also developed MPEG Surround codec that will be based on AAC+ technology with bitrates in the 48-128kbps domain, 5.1 channels (!) and internet streaming.

Encoding of MP3 Surround

There are two ways of encoding MP3 Surround files:

• mp3sEnc: encoding 1 mono WAV-file --> mono MP3, 1 stereo WAV-file --> stereo MP3; by encoding one interleaved 6-channel WAV or by encoding five (5.0) and six (5.1) mono WAV files --> 5.1 MP3 Surround. For TMB uploads this encoder is only useful as a free Fraunhofer stereo MP3 encoder, as there are no available broadcasts or non-commercial live DJ mix sets in 5.1 surround sound.

by running the FhG - MP3 Surround encoder and by enhancing already existing stereo MP3 files with the FhG - MP3SX converter.

WORK IN PROGRESS

In January 2006, Thomson and Fraunhofer IIS also released two new companion technologies: Ensonido, which allows playback of MP3 Surround 5.1 channel sound through stereo headphones, and MP3 SX, which upgrades standard stereo mp3 file to mp3 surround files.

External links

• http://all4mp3.com Software, demos, information, and various mp3 resources
• http://mp3surround.com - Demo content, information and evalution software